Measured feedback-induced intensity noise for 1.3 µm DFB laser diodes

An experimental set-up has been described, allowing for reliable relative intensity noise (RIN) measurements for a wide feedback range. It could be verified experimentally for DFB lasers that the transition to the coherence collapic regime occurs at significantly larger feedback levels, if the laser is operated at larger optical powers. Furthermore, it has been noted that a large coupling strength κL in DFB lasers is beneficial for improved stability against optical feedback.